1. Field of the Invention
The present invention relates to a wireless field device, a device management system performing management of the wireless field device, and a device management method.
Priority is claimed on Japanese Patent Application No. 2010-286883, filed Dec. 24, 2010, the content of which is incorporated herein by reference.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
A field device is a common designation of a sensor device such as a flowmeter or a temperature sensor, a valve device such as a flow control valve or an on-off valve, an actuator device such as a fan or a motor, or other devices installed at a plant or a factory. Most existing field devices perform transmission and reception of various signals such as measurement signals or control signals via wired field buses installed in a plant, and the like, but wireless field devices conforming to International Society of Automation (ISA) 100.11a, which is a wireless communication standard for industrial automation established by the ISA, are recently being implemented.
A communication system conforming to the wireless communication standard ISA100.11a generally includes the wireless field device, a wireless gateway, and a device management apparatus. The wireless gateway forms a wireless network with the wireless field device, thereby controlling an operation of the wireless field device participating in the wireless network and also performing collection of a variety of data obtained by the wireless field device, and the like. The device management apparatus is connected to the wireless gateway through a communication line, and performs management of the wireless field device via the wireless gateway.
In order to cause the wireless field device to participate in the wireless network, it is necessary to perform an operation of setting device information called “provisioning” on the wireless field device in a participating side, and an operation of registering device information specifying the wireless field device having performed “provisioning” in the wireless gateway in a side in which participation is made. “Provisioning” for the wireless field device is performed by a worker using, for example, a device called a provisioning device capable of infrared communication with a wireless field device, and the registration operation in the wireless gateway is performed by a manager using the device management apparatus.
A wireless field device for which the same device information as that registered in the wireless gateway is set is permitted to participate in the wireless network by the wireless gateway. A wireless field device for which device information other than that registered in the wireless gateway is set is denied participation in the wireless network by the wireless gateway. Also, in another technology field, Japanese Unexamined Patent Application, First Publication No. 2008-192158 discloses technology to improve security for re-provisioning and re-programming of a handset.
When provisioning is performed for a wireless field device participating in a wireless network through a communication path established to a wireless gateway, and setting information such as communication setting information required to perform wireless communication or the above-mentioned device information is changed, the communication path to the wireless gateway is disconnected. Likewise, if registration information registered in a wireless gateway is changed when wireless field devices participating in a wireless network are present, a communication path for a wireless field device is disconnected.
As mentioned above, a registration operation for a wireless gateway is performed by a manager using a device management apparatus connected to the wireless gateway through a communication line, and thus registration information is not often considered to be changed incorrectly. However, provisioning for a wireless field device is performed through infrared communication using a provisioning device, and the provisioning device is manipulated by an unskilled worker as well as a skilled worker. Thus, it is probable that setting information in a wireless field device is changed incorrectly by incorrect manipulation of a worker, and the like.
Furthermore, setting information set in a wireless field device may not only be changed incorrectly by incorrect manipulation of a worker, and the like, but also intentionally changed by a malicious worker. When such a change of setting information is made for a wireless field device installed in a plant, and the like, there may be a situation in which an operation of the plant, and the like should be stopped, and thus there is a problem of safety.